New-Tech Europe Magazine | Oct 2017 | Digital Edition

will be a suitable regulator available off-the-shelf to meet the voltage requirements. Obviously, the regulator must be able to deliver the power required by the load. Regulator power is typically specified by a maximum output current. Input and Output Ranges Although applications often require a specific voltage, others will require an adjustable output. This might be because the loads change – for example in a piece of test equipment – or it may be that the load is supplied by a long cable, and the voltage needs to be trimmed a little higher than required by the load to compensate for the voltage drop across the cable. Input voltage ranges are particularly important for applications such as battery-powered systems. In an automotive application, a nominal 12V battery might deliver 12.5V at full charge and drop to 10V or less as the battery discharges. A regulator with a narrow input range may no longer function as the battery voltage drops, meaning that the full capacity of the battery cannot be used. Ensuring a sufficiently wide input range is therefore an important criterion for selecting your regulator. Choosing wide input regulators also has another benefit: they can also reduce inventory costs as a single regulator can be used in a variety of different situations. Efficiency Efficiency is one of the criteria for

Figure 1: Battery Output Voltage Variations

Noise

most power systems designed today. Selecting a regulator with high power losses can make it almost impossible to meet efficiency goals. It’s important to also remember that regulator efficiency is not constant: typically, the efficiency of the regulator will fall dramatically as the step-down or step-up ratio increases and as the current drawn from the output decreases. Modern regulators, such as those based on Vicor’s Zero Voltage Switching (ZVS) topology offer inherently high efficiency and are more consistent across the whole operating range.

Switching provide high efficiency, but the switching circuit generates noise. In some systems, particularly those with sensitive analog components, the power supply noise can limit overall performance. Unnecessary electronic noise can also make it more difficult to achieve EMC certification. As with efficiency, the regulator topology is key to achieving low noise: it’s much easier to use a component that doesn’t generate noise than it is to try to filter that noise out. ZVS, for example, is regulators

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